Rotary radial piston machines



Dec. 14, 1965 K. EICKMANN 3,223,046

OTARY RADIAL PISTON MACHINES Filed Oct. 10, 1962 5 Sheets-Sheet 1 Fig.3

B I T (Pa i E m /W52)? K. EICKMANN ROTARY RADIAL PISTON MACHINES Dec. 14, 1965 I 5 Sheets-Sheet 3 Filed Oct. 10, 1962 R m R. QM vm L m INVENTOR. KARL E/C/(MA/V/V Dec. 14, 1965 I ElCKMANN 3,223,046 r ROTARY RADIAL PISTON MACHINES Filed Oct. 10, 1962 5 Sheets-Sheet 4 1}, INVENTOR.

KARL E/C/(MANN Dec. 14, 1965 K. EICKMANN 3,

ROTARY RADIAL PISTON MACHINES Filed Oct. 10, 1962 5 Sheets-Sheet 5 m 5, h2g7 United States Patent 3,223,046 RGTARY RADIAL PISTON MACHINES Karl Eiclnnann, 24-20 isshiki Hayama-machi, Miuragun, Kanagawa-ken, Japan Filed (Bet. 1t), 1962, Ser. No. 229,644 Claims priority, application Germany, Oct. 13, 1961, R 64,364 13 Claims. (Cl. 103-161) This invention relates to fluid operated radial piston machines such as hydraulic or pneumatic pumps, motors, transmissions or the like wherein cylinder cells are periodically drawing in and expelling fluid during operation under power. Such kind of machines have been known heretofore and are operating especially as oil-hydraulic pumps, oil-hydraulic motors, oil-hydraulic gear transmissions, rotary pneumatic machines, rotary pneumatic motors, compressors, rotary steam motors, rotary combustion engines, and the like.

In such heretofore known rotary radial piston machine a plurality of substantial radial cylinders is provided in a rotor, and pistons are moved in these cylinders during operation of the machine under power substantially radially inwards and outwards, thereby increasing and decreasing the volume of the cylinder cell inside of the respective cylinder wherein the respective piston is located. However, such former piston-piston shoe assemblies had deformations under high pressure, needed differential piston designs of different diameters, or failed to be stable under high load.

It is therefore an object of the invention to improve such machines and to provide a positive guide of the pistons during radial reciprocation thereof, and capable of exerting radial outwards traction forces and very high radial inwards pushing forces by means of a pivotally interconnected piston and piston and shoe assembly.

Another object of this invention is to provide a pivotally interconnected piston and shoe assembly which is simple in design and easy to build.

A further object of the invention is to provide such a piston and shoe assembly which is able to provide relatively large piston strokes compared to the dimensions of the machine by means of enabling parts of the shoe to move radially of the rotor into the respective cylinder.

A still further object of the invention is an improved guiding of the piston shoes by respective guide faces.

According to another object of the invention, radially opening fluid balancing recesses are provided between the outer faces of the piston shoes and inner faces of guiding rotating ring, and/ or between the shoe and piston.

in order to reach the objects of the invention each piston is, according to the primary embodiment of the invention, provided with a transverse bore extending normal to the axis of the respective piston and extending with equal radius diametrically through the whole piston, and an axially extending slot is provided on each piston extending from the outer end of the piston into such normal bore of the respective piston. Each piston shoe is provided with a partially cylindrical swing member or trunnion, a narrowed shoe supporting extension from the trunnion and shoe guide members. The partially cylindrical swing member of each respective piston shoe is located in the transverse bore of the associated piston, and the length of the swing member or trunnion is less than, but nearly equal to the diameter of the piston.

Each cylinder extending radially of the rotor has its outer end formed with slot extending axially and diametrically thereof. These slots, and the narrowed shoe bars and/or shoe extension members, are so dimensioned that the narrowed shoe bar and/or extension members of the respective piston shoes are able to enter into the associated slot of the rotor.

"ice

It is therefore an important feature of the invention that the pistons and the piston shoes are able to enter radially into the respective cylinder and/ or the respective slot therein at the radially innermost piston position, while on the other hand each piston is still guided in the associated cylinder at its radially outermost position. Therefore positive guiding of the piston in the respective cylinder is assured over a long stroke during travel in the respective cylinder. The radially inwards pushing forces of each piston shoe are directly transferred, by the partial cylindrical swing member or trunnion of the piston shoe to the inner part of the wall of the normal bore in the respective piston, thereby assuring capability of very high substantial radially inwards pushing force.

It has already been tried in the past to locate and to bear pivotal shoes directly or indirectly in rotary radial piston fluid machines, and it has already been tried to provide such piston shoes with guiding means. However, such prior attempts have failed to withstand the extremely high pushing forces which are needed in modern machinery and/ or they have failed to achieve the desired maximum stroke of the piston radially of the rotor. It is therefore an additional object of the invention to provide such piston shoe members in rotary fluid machines which permit both features in combination, maximal length of stroke and maximal capability of pushing force.

By the objects and features of the invention it is possible to eliminate friction on piston shoes and pistons and also to prevent deformations, heating, sticking and/or welding on pistons, piston shoes, and/ or their adjacent or guiding parts. Machines which are provided with the piston and shoe assembly of this invention are therefore capable of high power and they are effective in use and have a long useful life.

Other objects and features of the invention will become apparent from the following description taken in connection with the accompanying drawings which illustrate several embodiments of the invention.

In the drawings:

FIG. 1 is a longitudinal sectional view through an embodiment of the pivotally interconnected piston and shoe assembly of the invention, with parts of some components being shown in side elevation;

FIG. 2 is a sectional view taken on the line IIII of FIG. 1;

FIG. 3 is a radially outer end elevation view of the assembly shown in FIGS. 1 and 2;

FIG. 4 is a longitudinal or axial sectional view of the piston shown in FIG. 1;

FIG. 5 is a sectional view taken on the line V-V of FIG. 4;

FIG. 6 is an axial sectional view through the rotor of a rotary fluid machine with which the piston and shoe assembly invention may be used;

FIG. 7 is a diametrical sectional view of the rotor, taken on the line VII-VII of FIG. 6;

FIG. 8 is a longitudinal sectional view through another embodiment of a piston and shoe assembly in accordance with the invention;

FIG. 9 is a sectional view taken on the line IXIX of FIG. 8;

FIG. 10 is a transverse sectional view through the shoe shown in FIG. 8;

FIG. 11 is a sectional view taken on the line XI-XI of FIG. 10;

FIG. 12 is a transverse sectional view through the outer member of the shoe shown in FIGS. 10 and 11;

FIG. 13 is a sectional view taken on the line XIII- XIII of FIG. 12;

FIG. 14 is a radially outer end elevation view of the member shown in FIG. 12;

FIG. 15 is a side elevation view of a radially extending member of the shoe shown in FIG. 10;

FIG. 16 is a sectional view taken on the line XVI XVI of FIG. 15;

FIG. 17 is an axial sectional view through a trunnion member included in the shoe shown in FIG. 10;

FIG. 18 is a sectional View taken on the line XVIII XVIII of FIG. 17;

FIG. 19 is a side elevation view of the trunnion member shown in FIG. 17;

FIG. 20 is an end elevation view of the trunnion member shown in FIG. 19;

FIG. 21 is an axial sectional view of a nipple included in the shoe shown in FIG. 10;

FIG. 22 is an axial or longitudinal sectional View through a rotary fluid machine, such as a rotary hydraulic or pneumatic pump or motor, having the piston and shoe assembly, and associated guiding means, of the invention incorporated therein;

FIG. 23 is a sectional view taken on the line XXIII- XXIII of FIG. 22;

FIG. 24 is a longitudinal sectional view through another embodiment of piston and shoe assembly incorporating the invention;

FIG. 25 is a sectional view taken on the line XXV XXV of FIG. 24;

FIG. 26 is a longitudinal sectional view of a secondary embodiment of a piston and shoe assembly in accordance with the invention;

FIG. 27 is a sectional view taken on the line XXVII XXVII of FIG. 26;

FIG. 28 is a radially outer end elevation view of the piston and shoe assembly shown in FIG. 26; and

FIG. 29 is a plan view of a retainer ring used in the piston and shoe assembly shown in FIGS. 26, 27 and 28.

In the figures, element 1 is the piston. As can be clearly seen from FIGS. 4 and piston 1 is provided with the bore extending normal to the axis of the piston. It can also be seen from FIGS. 4 and 5 that a slot 12 extends inwardly from the radially outer end of piston 1, through piston 1 and radially into the bore 10. The upper part, or the radial outer part, of piston 1 is cut away to such extent that only the shoe seat extensions remain a part of the piston and partly surround the bore 10. Shoe seat extensions 13 are provided with break away surfaces 25 in order to prevent sharp corners thereon. The piston is provided with two shoe seat extensions 13, as can be clearly seen from FIGS. 4, 5 and other figures. The inner surfaces of the bores 10 are formed as the piston shoe seat. Those of the wall of bore 10 which are adjacent to the shoe seat extensions 13 form the traction seats 9. The center line or axis of bore 10 is shown at 11. Center line 11 is normal to the center line of the respective piston 1. The parts of piston 1 which are radially outwardly of center line 11 form the already cited shoe seat extensions 13 with the respective traction seats 9. The shoe seat extensions 13 with the traction seat 9 are important means of the piston and shoe assembly of the invention. This hecomes apparent if it is clearly understood that traction seats 9 are parts of the inner surface of bore 10 and which forms the shoe seat.

Since bore 10 is of cylindrical configuration with constant radius around the center line 11, the slot 12 must have a lateral dimension smaller than the diameter of the bore 10.

It can be seen from FIGS. 1, 2, 3 and others that the pivotal shoe 2 is connected to and borne by piston 1. Shoe 2 is provided with a cylindrical swing member or trunnion 3 and a narrowed shoe bar or stem 4. The narrow shoe bar 4 extends upwards, or radially outwards relative to the rotor, from the cylindrical swing member 3, and its lateral dimension is smaller than the diameter of the respective cylindrical swing member 3. The cylindrical swing member 3 is of cylindrical configuration with a constant radius around its axis. The narrowed shoe bar 4 is, or maybe, integral with the cylindrical swing member 3. The diameter of the cylindrical swing member 3 is substantially equal to, or somewhat smaller than the diameter of the respective bore 10 of the associated piston 1, but is larger than the width of the respective slot 12. Therefore, cylindrical swing member 3 can be inserted into the respective bore 10 and moved therein parallel to the axis 11, and cylindrical swing member 3 can swing or pivot around its own axis to a limited extent while it is borne and located inside of bore 10.

Thus, according to this invention, if shoe 2 and piston 1 are assembled together, shoe 2 is borne by piston 1 and able to swing around the axis of its cylindrical swing member to a limited extent. As shoe 2 is borne by piston 1 and able to swing around the axis of its cylindrical swing member 3, very high radially inwardly directed forces can be transmitted from shoe 2 to piston 1. This transmission of radially inwardly directed forces takes place between the outer cylindrical surface of cylindrical swing member 3 and the cylindrical wall of bore 10 of the respective piston 1. It is a special feature of this invention that the mentioned deformations of known pistons or piston shoes are prevented. But the piston and shoe assembly of this invention is not only able to transmit radially inwardly directed forces but also able to transmit radially outwardly directed forces. The transmission of radially outwardly directed forces takes place between the traction seats 9 of the shoe seat extensions 13 and the adjacent parts of the outer surface of the respective cylindrical swing member 3. Therefore, if shoe 2 moves radially outwardly, it draws piston 1 also radially outwardly.

Upwards or radially outwards of the narrowed shoe bar 4 the shoe central member 5 is located, and can be 'integral with narrowed shoe bar 4 and cylindrical swing member 3. The shoe central member 5 is provided with shoe extension members 6 which extend parallel or substantially parallel to the axis of the respective cylindrical swing member 3 in both directions. Cylindrical swing member 3, narrowed shoe bar 4 and shoe central member 5 are shorter in width than the diameter of the respective piston 1, narrowed shoe bar 4 and shoe extension members 6 are smaller than the respective slot 12 and shoe central member 5 is smaller than the respective slot 19. The shoe extension members 6 can be provided with extension members 17. Extension members 17 and/or shoe extension members 6 may be integral with shoe central member 5, narrowed shoe bar 4 and cylindrical swing member 3. However if extension members 17 are provided, that they are spaced axially from shoe central member 5, respective to the axis of rotor 21. Outer guide faces extend over shoe central members 5, over all shoe extension members 6, and, if extension members 17 are provided, also over extension members 17. Inner guide faces 8 are provided on shoe extension members 6, or on extension members 17, or on all of them. Both shoe extension members 6 and/ or all tangential extension members 17 are preferably provided with axial end faces 24.

The outside diameter of piston 1 is the piston wall or outer surface. The piston wall extends also over the part of the piston where bore 10 is located. The respective wall forms the extended piston wall 26 adjacent bore 10.

As can be especially seen from FIGS. 6 and 7 the rotor 21 is provided with substantially radially extending cylinders 18, which are common in the art. Each cylinder 18 is provided with a slot 19 extending axially thereof. The axial extending slots 19 are able to receive the respective cylindrical swing member 3, narrowed shoe bar 4, shoe central member 5 and/or shoe extension members 6. The slots 19 extend radially from outside into rotor 21, extending substantially parallel to the aXiS Of rotor 21.

and through the respective cylinder 18 and axially through rotor 21. The radial outer part of rotor 21 is so much narrowed in axial direction that the part defining the slots 19 is narrower than the diameter of the cylinders 18, thereby forming the narrowed outer part 60. The cited axial extending slots 19 are smaller than the diameter of the respective cylinder 18 through which the respective axial extending slot 19 extends. Therefore a part of the wall of the respective cylinder 18 remains undisturbed by the axial extending slot 19. This undisturbed part of the wall of the respective cylinder 18 forms the radial extending guide wall 29. If piston 1 is inserted into cylinder 18, the outer wall of piston 1 is guided by the wall of cylinder 18. Piston 1 is, a known in the art, of substantially equal or somewhat smaller diameter than the diameter of cylinder 18. Piston 1, its piston wall and/or its extending piston wall 26 is therefore closely fitting and tightly sealed, but able to slide parallel to the axis of cylinder 18 located, guided and borne in cylinder 18 during travel of piston 1 substantially radially inwards and outwards in the respective cylinder 18 by the walls of cylinder 18 and the radial extending guide walls 20. This fact enables very large piston strokes and a stable guiding of the respective piston. It is also possible to bear and guide tangential forces, or components of forces, which are normal or almost normal to the axis of the respective piston 1.

As will be seen from FIGS. 22 and 23, rotor 21 is located, as commonly known, inside of a casing 52 of the machine. Shaft 53 is borne by bearings 55. Shaft 53 and rotor 21 may be integral or may be connected together by clutches 56. Therefore shaft 53 can drive rotor 21 or rotor 21 can drive shaft 53. This is generally known in the art. A control pintle 54 may be provided in a center bore of rotor 21, and passages 58 and 59 may be provided in pintle 54. Fluid, like gas or liquid, may pass through one of the pintle passages 58 or 59 into respective cylinders 18 or out of them through the other of the said pintle passages 58 and 59. Such passage of fluid is also known in the art. An adjustment device 57 with its plurality of parts can also be provided in casing 52 for adjustment of the stroke of pistons 1. If the machine has no adjustment device 57, then the guide members for guiding the pistons or shoes radially outwards or inwards may be fixed.

Bearings 47 may be located inside of adjustment device 57. According to the embodiment of FIGS. 22 and 23 of the invention, at least two support rings 43 are provided in the machine and each support ring 43 is borne by a respective radial bearing 47. Said support rings 43 are therefore able to rotate. As can be seen from FIGS. 22 and 23, this embodiment of the invention is provided with a rotation or spacer ring 42 which is located between both support rings 43 and borne by them, and rotates together with them if the machine operates under power. The said rotation ring and the said support rings form the guide members of the machine. Rotation ring 42 is provided with a radially inner guide face or faces 46, and support ring 43 can be provided with lateral guide faces 45. Each support ring 43 is preferably provided with at least one radially outer guide face 44. According to this invention, as can be seen from FIGS. 22 and 23, the outer guide faces 7 of shoes 2 conform to the rotation ring 42; and they are borne and guided by the guide inner face 46 of rotation ring 42. Thus they can slide peripherially with respect to rotation ring 42 or inner guide face 46. Axial end faces 24 of the pivot shoes 2 can be guided by the guide faces 45 of support rings 43. The inner guide faces 8 of the pivot shoes 2 are guided by the radially outer guide faces 44.

Thus if the machine operates under power and if the guide member inner face 46 is eccentrically located with respect to the axis of rotor 21 the distance from the axis of rotor 21 to the guide member inner face 46 changes during a rotation of the rotor 21. If the said distance example.

decreases the respective shoes 2 are forced by guide member inner face 46 to move radially inwards. The sub stantial radially inwardly directed pushing force is transmitted from guide member inner face 46 to outer guide face 7 of shoes 2 and by the outer surface of cylindrical swing member 3 to the wall of the respective bore 10 of the associated piston 1 and thereby transmitted from the guide member inner face 46 via the respective shoe 2 to the associated piston 1. It is a special feature of this invention that the shoe 2 is so very strong, and also that, under extremely high pushing or traction forces, deformations an-d/ or breaking of pistons or slid shoes are prevented. On the contrary, if the said distance from the axis of rotor 21 to the guide member outer faces 44 increases during rotation of rotor 21, the inner guide faces 8 of the respective shoes 2 are forced by the guide member outer faces 44 to move substantially radially outwards. The radial outward movement of the respective shoe 2 is transmitted by the outer surface of cylindrical swing member 3 to the traction seats 9 of the respective piston 1.

Therefore, according to this invention, a positive guiding, radially outwards and radially inwards, of the shoe 2 by at least the guide member inner face 46 and guide member outer face 44 is assured. The embodiment of FIGS. 22 and 23 shows rotary guide members consisting of rotation ring 42 and support rings 43. A system of rotary guide members provides the important feature that the relative velocity between the outer guide faces 7 and the guide member inner face 46 is comparatively small, since the guide members are rotating with an angular velocity substantially equal to the angular velocity of rotor 21. However, the embodiment of FIGS. 22 and 23, or other rotary guide member systems, are only for The piston and shoe assembly of this invention can also be used in fluid machines with non-rotary guide members, if such guide members are provided with guide member inner faces 46 and guide member outer faces 44.

Another important feature of the improved piston and shoe assembly of the invention is clearly visible in FIG. 23. From FIG. 23 it can be seen that, in its radial innermost position, piston 1 is entirely received in the respective cylinder 18. Also cylindrical swing member 3, narrowed shoe bar 4, and shoe central member 5 can enter the respective cylinder 18. Shoe extension members 6 can enter into the slots 19 and/or extension members 17 can pass radially inwards beyond the outer diameter of rotor 21, while narrowed outer part of rotor 21 can enter the space between extension members 17 of shoes 2. Therefore, according to this invention, piston 1 and slide shoe 2 can move radially inwards until the outer guide face 7 has nearly the same distance from the axis of rotor 21 as the adjacent part of the outer diameter of rotor 21. On the other hand, piston 1 and shoe 2 can, as will be also apparent from FIG. 24, move very far radially outwards in its radial outmost position. Also, during far radial outward movement, piston 1 is guided by the radially extending guide walls 20. Even during extremely large strokes, the piston and shoe assembly of this invention is stable and able to withstand and transmit very high substantially radial inward forces because even in the cases of the largest. angular displacement of shoe 2 respective to piston 1, the resultant of the pushing forces which is substantially normal to the adjacent part of the guide member inner face 46 meets the outer wall of piston 1, or the extending piston wall 25, substantially at the wall of cylinder 18 or at the radial extending guide wall 20. This stability provides the possibility of very high pushing forces.

As is seen from the figures, each part of the guide members, shoes, or pistons which have to transmit pushing or traction forces are engaged with each other at corresponding, large dimensioned, faces. This provides the ability to slide relatively to each other with less friction and at the same time to transmit large forces.

It is therefore possible according to this invention to provide rotary radial piston machines with very high power and displacement, since the invention enables unusually long piston strokes. Due to the possibility of large piston strokes in rotary fluid machines according to this invention, such machines can be built relatively simple and with less expenditure of work and material. Since on the other hand large pushing and traction forces are possible in machines according to this invention, high pressures can be used in such machines. The narrowing of the outer dimension of the machine, together with the stability of the guide system, the pivotal connections of the shoes and pistons, and the large piston stroke makes high output and power of the machine possible at relatively less friction. Very high eificiency of the machine can thereby be obtained. The stability of the shoe, and the guiding thereof by guide faces, insures a long useful life of the machine and its parts. All deformations of piston shoes or piston bolts of usual machines are prevented, and also guiding parts of or for pistons, which needed a certain space and relatively high relative velocity against adjacent parts in earlier machines, are prevented by this invention.

Other objects and features of the invention will also become apparent from the figures. Piston passages 15 can be provided in shoe 2, and an outer recess or outer recesses 23 can be provided in the outer guide face 7 thereof. Outer recess 23 can extend in shoe central member 5, or also into shoe extension members 6, or also into extension members 17. Shoe passage 16 can be connected to outer recess 23 and also to piston passage 15. Therefore fluid can enter from cylinder 18 through piston passage 15 and through shoe passage 16 into outer recess 23. This fluid is able to lubricate the outer guide faces 7 and/ or the guide member inner faces 46 or both together. Outer recess 23 can be dimensioned large enough that forces of fluid under pressure therein are able to balance partially or totally the forces of fluid which act on the inner end of piston 1 to move the latter out from cylinder 18. In such cases, the radially inward pushing forces are taken by the bottom of outer recesses 23 instead by the outer guide faces 7. Lubrication or balancing recesses may be also located in the inner guide faces 8 and communicated to outer recesses 23 or to shoe passage 16. Center recess 22 can be provided between piston 1 and cylindrical swing member 3, and can extend into piston 1 or into cylindrical swing member 3 or into both, and can connect piston passage 15 and shoe passages 16 with each other. Fluid can enter the center recess or recesses 22 and lubricate the wall of bore and the outer face of cylindrical swing member 3, or both of them. The forces of fluid in center recess 22 are also able, at least partially, to reduce the forces between shoe 2 and piston 1 during radial inward pushing of shoe 2 and piston 1. If the respective recesses 16, 37 and passages 15, 16 are suitably dimensioned and located, it can be attained that forces of fluid acting radially outwards on the bottom of piston 1 plus centrifugal forces of piston 1 and pivot shoe 2 can be almost or partially balanced by counteracting of forces of fluid under pressure in outer recess 23. The piston and shoe assembly is then almost floating between beds of fluid under pressure, and friction between outer guide face 7 and guide member inner face 46 is substantially reduced. Such pressure fields in outer recesses 23 are positive in operation, since the stability of the shoe prevents deformation or disturbance of the outer recesses 23 under load.

The embodiment of FIGS. 24 and 25 shows that it is possible according to this invention to restrain a shoe 2 from sliding axially inside of bore 10 of piston 1. In order to eflect this, cylindrical swing member 3 of shoe 2 is inserted by movement parallel to the axis of bore 10,

into bore 10 until located in an almost central position. After shoe 2 has reached its location, piston stopper 48 is inserted into a center bore of piston 1 and pushed far enough through the center bore of piston 1 that a part of piston stopper 48 extends into the shoe inner recess 37. Inner recess 37 is located in the cylindrical swing member 3 and according to the embodiment of FIGS. 24 and 25, has an extent such that shoe 2 can pivot inside of bore 10 of piston 1 in a limited but necessary extent without being stopped by piston stopper 48. Since piston stopper 48 extends into inner recess 37, shoe 2 is prevented from moving parallel to the axis of bore 10 by engagement between stopper 48 and inner recess 32. Piston stopper 48 can be provided with a stopper seat or shoulder 50 which determines the location of piston stopper 48 in piston 1 and the inner recess 37. A retaining ring 51 can be inserted or pressed into a circumferential recess in the center bore of piston 1, and can fasten and fix piston stopper 48 in piston 1, and thereby accidental disassembly of piston 1 and piston stopper 48 is prevented during operation of the machine. Stopper passage 49 can be provided inside of piston stopper 48, and carry out the functions of :piston passage 15. The bottom of piston 1 can be provided with a taper or other kind of dead space filler or fillers in order to extend into the rotor apertures at the innermost piston position. Thereby dead space in cylinder cells and cylinder apertures can be prevented and internal compression losses in fluid can thereby be reduced or diminished.

The embodiment of the invention which is shown in FIGS. 8 to 20 is directed to piston shoe 2 consisting of and assembled from a number of pieces. The feature of this kind of piston shoe is that it can be easily manufactured by usual machine tools. This embodiment makes it also possible to use different kinds of materials for cylindrical swing members 3 and the shoe extension members. However, if the embodiment of FIGS. 8 to 20 is used, it must be considered that the outer face of swing cylinder 28 of this embodiment is comparatively smaller than that of the cylindrical swing member 3 of the other embodiments. This narrows the capability for high pushing and/ or traction forces, which factor must be considered in practice.

Swing cylinder or trunnion 28 is provided on its axial ends with stub shafts 36, one on each axial end. A passage 31 is also provided in swing cylinder 28, and takes over and carries out the functions of shoe passage 16 of other embodiments. Swing cylinder 28 can additionally be provided with the bore 38 which extends radially from outside into swing cylinder 28. Shoe outer member 27 carries out the functions of shoe central member 5 and/ or of narrowed shoe bar 4 of the other embodiments, and can also be provided with shoe extension members 6 in both axial directions. The shoe outer member 27 can also be provided with the passage 16, with the outer guide face '7 and with the outer recess or recesses 23. The functions of these parts are already known from the other embodiments of the invention. Additionally, an inner seat 41 is provided on shoe outer member 27 and corresponds to the outer diameter of swing cylinder or trunnion 28. In addition thereto, the shoe outer member can be provided with a bore 40. Bore 40 and piston shoe bore 48 receive or contain the connection or nipple 29. This connection pipe 29 can be provided with passage 32. Conection pipe 29 may be inserted into bore 38 and outer member 27 may be set onto swing cylinder 38, whereby connection pipe 29 extends into bore 40. By this kind of assembly, relative axial movement and peripheral movement between swing cylinder 28 and outer member 27 are prevented by the connection tube 29 between them. Passage 16 of outer member 27, passage 32 and passage 31 take over and carry out the functions of passage 16 which are known from the other embodiments of this invention. Lateral shoe members 30 are provided with bores 33, so designed and located that they can receive stub shafts 36 of swing cylinder 28, preferably with close fit. Lateral shoe members 30 are also provided with guide extensions 35, and guide extensions 35 are provided with outer faces 34 and with inner guide faces 8. The lateral shoe member outer seat 34 seats radially into the shoe extension member 6 and/or the extension members 17 of shoe outer member 27. The inner guide faces 8 of lateral shoe members 30 take over and carry out the functions of the inner guide faces 8 which are known from the other embodiments. Each lateral shoe member 30 is adapted to a respective axial end of shoe outer member 27 and swing cylinder 38, thereby receiving the respective stub shaft 26 of swing cylinder 28. Thereafter, the assembly of the embodiment of FIGS. 8 to '20 is completed and outer member 27, swing cylinder 28, connection pipe 29, and the lateral shoe members 30 are togtther forming a shoe substantially similar to that in the other figures. If the embodiment of pivot and shoe assembly as in FIGS. 8 to 20 is assembled in a rotary fluid machine, disassembly of the parts is prevented by the guide member side faces 45 and guide member inner faces 46.

A secondary embodiment of the invention, which is shown in FIGS. 26 to 29, is connected by the ball form swing member to a spherical shoe seat which is provided in piston 61. Piston shoe 2 is provided with a ball formed swing member 62, and ball form swing member 62 is located in and borne by the spherical shoe seat in piston 61. A recess is provided extending radially of the rotor from the outer end of piston 61 into the spherical shoe seat of piston 61. The said radial extending slot or recess is preferably of cylindrical configuration and may be provided with circumferential grooves or with one circumferential groove extending into piston 61. The narrowed shoe bar 4 extends from the piston shoe swing member 62 into shoe central member and connects both together. Piston swing member 62 is preferably fastened in piston 61 by retainer snap ring 63, which may snap into a groove in piston 61. Retainer snap ring 63 may be provided with inner retainer member 64 which may be correspondingly formed and dimensioned for sliding engagement with the ball form of swing member 62. Retainer ring 63 may also be provided with a number of outer retainer members 65 which are suitably designed to engage in the corresponding ring groove in piston 61. Slot 66 can be provided in retainer snap ring 63 in order to make the retainer snap ring 63 more flexible in radial direction. The retainer snap ring 63 is preferably made of spring material in order to enable deformation for smooth insertion or pressing into the respective or ring groove of piston 61. The other parts such as 15, 37, 4, 5, 6, 16, 23, and 17 are already shown in the other figures and carry out the same functions as in FIGS. 1 to 25. As shown in FIGS. 26 and 28, pressure fluid limitation grooves 67 are provided in the outer guide face 7 of shoe 2. Similar pressure fluid limitation grooves can also be provided in the shoes of FIGS. 1 to 25. If fluid under pressure is present in the outer recess 23, then fluid enters into the clearance between outer guide face 7 of pivot shoe 2 and the cooperating guide member inner face. A pressure drop appears between the said faces, with higher pressure adjacent outer recess 23 and with pressure gradually decreasing with increasing distance from outer recess 23. By means of pressure fluid limitation grooves 67, the size of the pressure drop area and the force of the pressure of fluid from outer recess 23 can be limited. This limitation is important for calculation and designing purposes. The location and size of pressure fluid limitation grooves 67 has an important influence in the size, location and power of forces of fluid under pressure acting substantially radially inwards against the respective shoe 2.

The embodiments of FIGS. 8 to 20 and that of FIGS. 26 to 29 are only secondary embodiments of the invention. The feature of the secondary embodiments of the invention is that they can be machine with usual machine tools. The secondary embodiment of piston and shoe assemblies is therefore sometimes preferred for rotary fluid machines of limited pressure. But the secondary embodiments of the invention cannot attain the maximum radial inward pushing force which can be handled by the piston and shoes assemblies of FIGS. 1 to 5 and 22 to 25 assure a maximum of bearing surface area of the faces with which the shoe is borne in the piston. The maximum possibility of radial inward pushing force is therefore assured in the primary embodiments of the invention. The secondary embodiments of the invention are different from a primary embodiments of the invention by the size and form of the shoe seats or pivots, because they are of smaller area than in the primary embodiments and the capability of radial inward pushing forces is therefore consequently lesser than in pistons and shoes of the primary embodiments. This factor must be taken into account in actual applications.

This improvement of pistons, shoes and guiding means for pistons and/or shoes of the invention are very effective and can be used in oil hydraulic pumps, motors, transmissions and other liquid operated pumps, motors, transmissions or the like, and they can also be used in such kinds of rotary piston machines which operate with gases or vapors as the working medium such as gas, steam, or air compressors or engines, rotary combustion engines, or the like. The embodiments of the invention can be used in such machines wherein fluid passes into and out of the cylinders by means of passages in pintles, control bodies, control faces, or the like, as well as in machines where valves control entrances and/ or exits of the cylinders. It will be apparent to those skilled in the art that it is equally applicable to other similar machines. It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention.

I claim:

1. In a rotary fluid machine having a rotor formed with angularly spaced radial bores constituting cylinders, pistons reciprocable in said cylinders during rotation of said rotor to cyclically vary the effective volumes of the cylinders inwardly of the pistons for displacement of fluid into and out of said cylinders, a housing mounting said rotor, and guide means in said housing operable to reciprocate said pistons responsive to rotation of said rotor: the improvement comprising said rotor having an axially narrow peripheral portion centered on said cylinders and having a width, axially of said rotor, less than the internal diameter of said cylinders whereby to form slots extending radially outwardly from the cylinders and parallel to the rotor axis; each piston having a cylindrical bore extending transversely thereof adjacent its outer end, and a slot extending from said bore through the outer end of said piston, said last-named slots and bores extending parallel to the rotor axis; guide shoes cooperable with said guide means and each operable to reciprocate a respective piston, each guide shoe including a substantially cylindrical trunnion having direct seating engagement in the bore of the respective piston for transmission of radial forces directly from each shoe to the associated piston, an arcuate shoe portion interfitted with said guide means, and a stem connecting the trunnion to the shoe portion; and means restraining each trunnion against movement radially outwardly of its associated piston whereby said guide shoes may exert direct compression and traction forces on the associated pistons; the dimensions of each trunnion, stem and shoe portion, circumferentially of the rotor, being less than the diameter of the associated piston; whereby, in the radially inward limiting position of each piston, the trunnion, stem and shoe portion of its associated shoe may enter substantially fully into the rotor slot of the associated cylinder; whereby, for a given rotor diameter, the effective stroke of each piston is substantially increased.

2. In a rotary fluid machine, the improvement as claimed in claim 1, in which said guide means has a radially inwardly facing circular guiding surface, each arcuate shoe portion having a radially outer guide surface concentric with and engaging said radially inwardly facing guide surface.

3. In a rotary fluid machine, the improvement as claimed in claim 2, in which, in said radially inward limiting position of each piston, said radially outer guide surface is at a distance from the rotor axis substantially equal to the rotor radius.

4. In a rotary fluid machine, the improvement as claimed in claim 2, said guide means further including a radially outwardly facing guide surface concentric with said radially inwardly facing guide surface, and each arcuate shoe portion including a radially inwardly facing guide surface engageable with said radially outwardly facing guide surface of said guide means; whereby said last named interengageable surfaces provide for exerting traction on the associated pistons.

5. In a rotary fluid machine, the improvement claimed in claim 1, in which the axial length of each trunnion is less than the axial length of the bore receiving the same.

6. In a rotary fluid machine, the improvement claimed in claim 1, in which the outer face of each arcuate shoe portion is recessed.

7. In a rotary fluid machine, the improvement claimed in claim 6, including passage means extending through said arcuate shoe portion, said stem, said trunnion and the associated piston whereby to establish communica tion between said recessed portion of said arcuate shoe portion and the associated cylinder inwardly of the associated piston.

8. In a rotary fluid machine, the improvement claimed in claim 7, including recess means formed cooperatively in the innermost surface of each trunnion and the facing surface of the associated trunnion receiving bore.

9. In a rotary fluid machine, the improvement claimed in claim 7, including a recess formed in the innermost surface of each trunnion, said recess being centered on the passage in the associated piston and having a limited axial extent; and a tubular stopper means mounted in the associated piston and having an end projecting into the transverse bore in the piston and extending into said recess in said trunnion to limit axial displacement of the latter.

10. In a rotary fluid machine, the improvement claimed in claim 1, in which each trunnion and the associated arcuate shoe portion constitutes separate members; and means interconnecting each trunnion with its associated arcuate shoe portion.

11. In a rotary fluid machine, the improvement claimed in claim 10, in which each trunnion has a pair of pins extending axially from respective ends thereof; said connecting means comprising wing members on each arcuate shoe portion arranged to receive the pins of the associated trunnion.

12. In a rotary fluid machine, the improvement claimed in claim 10, including a passage extending diametrically of each trunnion and a passage extending through each arcuate shoe portion between the inner and outer surfaces thereof; and a tubular nipple seated in recesses in a respective arcuate shoe portion and a respective trunnion and interconnecting said passages.

13. In a rotary fluid machine, the improvement claimed in claim 1, the slot in the outer end of each piston having a width equal to the diameter of said bore; said restraining means comprising a snap ring seated in a groove in said slot and preventing radially outward movement of the associated trunnion; said bore being formed as a partially spherical seat to receive a partially spherically cooperating trunnion on an associated guide shoe.

References Cited by the Examiner UNITED STATES PATENTS 580,838 4/1897 Almond 91204 X 2,021,354 11/1935 Ernst 103161 2,220,636 11/ 1940 Bischof 103-461 2,427,224 9/1947 Morton 103-161 X 2,429,011 10/1947 Wylie 103--l61 2,552,449 5/1951 Overbeke 103-161 LAURENCE V. EFNER, Primary Examiner. 

1. IN A ROTARY FLUID MACHINE HAVING A ROTOR FORMED WITH ANGULARLY SPACED RADIAL BORES CONSTITUTING CYLINDERS, PISTONS RECIPROCABLE IN SAID CYLINDERS DURING ROTATION OF SAID ROTOR TO CYCLICALLY VARY THE EFFECTIVE VOLUMES OF THE CYLINDERS INWARDLY OF THE PISTONS FOR DISPLACEMENT OF FLUID INTO AND OUT OF SAID CYLINDERS, A HOUSING MOUNTING SAID ROTOR, AND GUIDE MEANS IN SAID HOUSING MOUNTING RECIPROCATE AND PISTONS RESPONSIVE TO ROTATION OF SAID ROTOR: THE IMPROVEMENT COMPRISING SAID ROTOR HAVING AN AXIALLY NARROW PERIPHERAL PORTION CENTERED ON SAID CYLINDERS AND HAVING A WIDTH, AXIALLY OF SAID ROTOR, LESS THAN THE INTERNAL DIAMETER OF SAID CYLINDERS WHEREBY TO FORM SLOTS EXTENDING RADIALLY OUTWARDLY FROM THE CYLINDERS AND PARALLEL TO THE ROTOR AXIS; EACH PISTON HAVING A CYLINDRICAL BORE EXTENDING TRANSVERSELY THEREOF ADJACENT ITS OUTER END, AND A SLOT EXTENDING FROM SAID BORE THROUGH THE OUTER END OF SAID PISTON SAID LAST-NAMED SLOT AND BORES EXTENDING PARALLEL TO THE ROTOR AXIS; GUIDE SHOES COOPERABLE WITH SAID GUIDE MEANS AND EACH OPERABLE TO RECIPROCATE A RESPECTIVE PISTON, EACH GUIDE SHOE INCLUDING A SUBSTANTIALLY CYLINDRICAL TRUNNION HAVING DIRECT SEATING ENGAGEMENT IN THE BORE OF THE RESPECTIVE PISTON FOR TRANSMISSION OF RADIAL FORCES DIRECTLY FROM EACH SHOE TO THE ASSOCIATED PISTON, AN ARCUATE SHOE PORTION INTERFITTED WITH SAID GUIDE MEANS, AND A STEM CONNECTING THE TRUNNION TO THE SHOE PORTION; AND MEANS RESTRAINING EACH TRUNNION AGAINST MOVEMENT RADIALLY OUTWARDLY OF ITS ASSOCIATED PISTON WHEREBY SAID GUIDE SHOES MAY EXERT DIRECT COMPRESSION AND TRACTION FORCES ON THE ASSOCIATED PISTONS; THE DIMENSIONS OF EACH TRUNNION, STEM AND SHOE PORTION, CIRCUMFERENTIALLY OF THE ROTOR, BEING LESS THAN THE DIAMETER OF THE ASSOCIATED PISTON; WHEREBY, IN THE RADIALLY INWARD LIMITING POSITION OF EACH PISTON, THE TRUNNION, STEM AND SHOE PORTION OF ITS ASSOCIATED SHOE MAY ENTER SUBSTANTIALLY FULLY INTO THE ROTOR SLOT OF THE ASSOCIATED CYLINDER; WHEREBY, FOR A GIVEN ROTOR DIAMETER, THE EFFECTIVE STROKE OF EACH PISTON IS SUBSTANTIALLY INCREASED. 